Method and apparatus for applying metallic sheaths to cables



May 20, 1941. 5, F066 2,243,031

METHOD AND APPARATUS FOR APPLYING METALLIC SHEATHS TO CABLES Filed May11, 1939 2 Sheets-Sheet 1 L. E. FOGG May 20, 1941.

METHOD AND APPARATUS FOR APPLYING METALLIC SHEATHS T0 CABLES Filed May11, 1939 2 Sheets-Sheet 2 p 3 W 9 @M W f w Patented May 20, 1941 METHODAND APPARATUS FOR. APPLYING DIETALLIC SHEATHS TO CABLES Leigh E. Folg,East Providence, a. 1., assignor to Kennecott wire and Cable Company,Phillipsdale, R. 1., a corporation Application May 11, 1939, Serial No.273,155

8 Claims. (Cl. 207-4) This invention relates to improvements in meth- Iods and apparatus for applying metallic sheaths to cables.

Heretofore in the art of applying metallic sheaths to electric cables,which sheaths ordinarily are of lead or lead alloy, considerable troublehas arisen from e presence of oxide and other foreign matter primpurities being present in the lead when it is extruded from the pressinto the form of a slteath about the cable and thus causing defects. Oneof the most serious reasons for the foreign matter causing troubleresults from the" fact that the sheathing press or lead press, as it iscalled, isof such limited capacity that it is unable to contain asufiiciently large charge of lead to extrude a sheath for a full lengthof cable. Therefore, as the sheathing press has to be recharged withmolten lead one or more times'in order to form a complete length ofsheath on a single length of cab1e,,there may be one or more welds orlocations along the sheath wherethe successive lead charges join in thesheath, and it is particularly at these locations that the most seriousdefects due to impurities occur. Although many eiforts have been made toeliminate the impurities from the lead in the press'and thus avoid thedifllculty of inferior and defective sheaths, this has not heretoforebeen satisfactorily accomplished.

I have found that by centrifugally treating the metal in moltencondition before putting it in the sheathing press, that the impuritiescan besubstantially entirely eliminated from the metal, so that aperfect sheath can be formed over a full length of cable, even at thelocations where the successive charges of lead merge together.

One object of this invention, therefore, is to provide an improvedmethod of substantially eliminating impurities from the metal in thesheathing press in order to make the sheath free from defects.

Another object of this invention is to provide improved apparatus forcarrying out the foregoing method.

With the above and other objects in view, as will appear to thoseskilled in the art from the present disclosure, this invention includesall features in the said disclosure which are novel over the prior art.

In the accompanying drawings forming part of the present disclosure, inwhich one way of carrying out the invention is shown for illustrativepurposes:

Fig. 1 is a schematic vertical sectional v ew illustratlng oneembodiment of an apparatus for carrying out the invention;

Fig. 2 is a cross sectional Fig. 1;

Fig. 3 is a cross sectional view on line 3-3 of Fig. l; and

Fig. 4 is a cross sectional view on line 4-4 of Fig. 1.

In the description and claims, the various parts and steps areidentified by specific names for convenience, but they are intended tobe as generic in their application as the prior art will permit.

Referring to the drawings showing the particular form of the inventionchosen for illustration, the apparatus illustrated, in the main,comprises a melting furnace I, a centrifugal separator Ii, a supply orstorage kettle or chamber view on line 2-2 of or tank l2, and asheathing press It.

The melting furnace ll may'be constructed in any suitable way, and isillustrated as having a suitable burner ll which can receive gas orother suitable heating medium through a pipe l8. Airinlet openings I 9in the casing Ii provide an ample supply of air to the burner I1, andexit openings 20 provide an adequate exit for the burned gases from theburner, If desired, the melting furnace I. may be, provided with asuitable cover lid, and a pipe lob for introduction of steam or hydrogenor other suitable fluid medium into the melting chamber l4 or forproviding a vacuum therein, to maintain a non-oxidizing or reducingatmosphere in contact. with the metal being melted in the meltingchamber l4 or otherwise minimize or preclude oxidation.

The centrifugal separator ll includes a lower fixed bearing 2| on whichis rotatably mounted a centrifugal bowl or cylinder 22, which bowl 22has a shaft 23 rotatably mounted in a fixed upper bearing 24 formingpart of a spider 25 having its rim portions 26 and 21 respectivelyfitting within, and resting upon the upper edge of, the

upper rim portion 28 of a storage or circulating pot has the parts 30,3|, 32 and part of coupling 33 1 carried thereon, so that when the cover34 is swung down to the position shown and locked by the bolt 31 and'nut 38, the parts of the coupling 33 are in driving engagement with oneanother, so that the motor 30 can rotate the centrifugal bowl 22. Aflexible or other suitable pipe or tube 39 leads through the cover orother suitable part of the tank 29 to provide for the introduction ofsteam or hydrogen or other suitable fluid medium or to provide a vacuumin the tank, to maintain a non-oxidizing or reducing atmosphere incontact with the metal being purified by the centrifugal separator orotherwise preclude or mini- 3 mize oxidation. The tank 29, at its lowerend carries the lower bearing 2| of the centrifugal 1 separator Thesheathing press or lead press l3 can be of any suitable or usual form,and in the form shown includes a cylinder 48 and a power-actuated pistonor ram 4| adapted to slidingly lit the inner cylindrical surface of thecylinder 49. The cable I 42 to be sheathed, is adapted to extendcompletely press |3 including the sheathing die at the far side of thepress, in a well-known in the art.

through the lower part of the sheathing manner that is usual and A pipe44 leads from the bottom of the melting |4 through a control valve 45 toa T 46,

and thence in one direction downwardly through a drain valve 41 and adrain pipe 48, and in the opposite direction upwardly through a pipesec- 'tion 49 to the interior passage 58 of the bearing 2| and into thecentrifugal cylinder or bowl 22. 1 One or more inlet or ingress ports oropenings 5| 1 provide ingress into the passage 59 leading to thecentrifugal bowl 22, from the interior 52 of the storage or circulationtank or kettle 29. The ingress openings 5| can becontrolledbyanysuitable valve means such, for example, as the rotaryvalve-sleeve 53 having an arm 54 provided with a slot 55 engaged by theend of a rod 56 slidably extending through a lead-tightpacking-connection 51 and carrying an operating knob 58. One

ports 59 are v or more egress or outlet openings or provided at theupper end of the centrifugal bowl with a channel leading from the outletopenings 59 of the centrifugal separator, thus entirely eliminating theuse of any storage or re-circulating tank. Or, a supply or storage tankor kettle for molten metal could be in the form of a separate sealedkettle.

When a charge of metal has been melted in the melting pot I4 and broughtto a desired temperature, the drain valve 41 is closed, valve-sleeve 53is rotated by the knob 58 to close the ports 5|, and control valve 45 isopened to permit the Y molten metal to flow from pot l4 through thepipes 44 and 49 into the interior 50 of bearing 22. The egress port orports will have a suitably smaller cross-sectional area than the ingressport or ports to ensure that V der remains fully charged with both leadand the separated impurities.

A pipe 60 leads from the interior 52 of the tank 29 through a controlvalve 6| and through the passage 62 into the interior chamber 63 of thecylinder of the sheathing press |3.

Although heat insulation has only been shown as surrounding the meltingpot, it will be appreciated that any other parts of the apparatus thatit is found preferable to have surrounded with heat insulation materialcan be readily so provided to aid in retaining the metal in moltencondition at all locations from the melting pot to the sheathingpress.Also, electrical or other suitable heating means may desired, to aid inmaintaining the metal in molten condition.

Instead of having the storage tank 29 surrounding the centrifugalseparator II, a storage tank or kettle could be arranged away from thecentrifugal separator with suitable piping leadthe centrifugal cylinbeprovided where ing from the outlet openings 59 of the separator 2| andinto the centrifugal bowl or cylinder 22, which when adequately full, isset into operation by starting the motor 25. The centrifugal forcecreated by the rotating metal in the rotating centrifugal cylinder 22causes the impuri-' ties, which are lighter than the molten metal, to beforced by the heavier metal to move inward toward the center of therotating mass of molten metal. As the mass of molten metal speeds up, itrises inthe centrifugal cylinder and starts passing out of the egressports 59. The molten metal which passes out through the egress ports 59drops down into the interior'of the tank 29 until the molten metal inthe tank 29 rises to such a height as is desired, whereupon the controlvalve is closed and the knob 58 is actuated to rotate the valve-sleeve53 to open the ingress ports 5|, whereupon molten metal flows by gravitythrough the ingress ports 5| and upwardly through the center opening toconstantly replenish the supply of metal that is being centrifugallypurified within the cylinder 22 and thrown out through the egress ports59. The egress ports 59 are of suitably less total area than the totalarea of the ingress ports 5| so that a suflicient amount of molten metalcan enter the centrifugal cylinder to maintain the latter adequatelyfull.

Thus, as the centrifugal cylinder 22 continues to rotate, the metal inthe vicinity of the cylinder wall moves up and flows out of the egressports 59, and other metal flows in the ingress ports 5|, thus bringingabout a circulation of the body of molten metal in the tank 29 to thussubject this mass of metal to repeated purification. If desired, at anytime, the centrifugal separator can have its rotation stopped, thevalve-sleeve 53 can be closed, and the drain valve 41 can be opened todrain out the lead within the cylinder 22 with,

the impurities contained therein.

Upon the control valve 6| being opened byturning the handle 61, purifiedlead can flow from the tank 29 through the pipe 69 into the interior 63of the sheathing press l3, the filling of the chamber 63 beingfacilitated by raising the ram 4| which tends to cause a vacuum. Ifundercut groove means 86 is avoided in the underface of the ram 4|, itwill aid in causing the residual lead adjacent the ram to be drawn upwith the ram, thus leaving the inner end of the passage 62 unobstructed.The control valve 6| is then closed by properly turning its handle Whenthe ram 4| is caused to move down under power to press the plastic metalin the chamber 63, plastic lead is formed into a solid metal sheath 64surrounding the cable 42, as the cable moves from left to right asindicated by the arrow in Fig. 1.

When the ram reaches the end of its downward movement, it is caused bythe operator to be actuated to be retracted upward again to draw in arenewed supply of molten metal. The

ram isthen again caused to move downward to force molten metal tocontinue to form another section of sheath about the cable 42. Theoperation is repeated as often as necessary to completely sheath acomplete length of cable.

Thus, it will be seen that by interposing a centrifugal separatorbetween a melting chamber and a sheathing press, whether or not anystorage tank is employed in connection with the centrifugal separator,all metal fed to the sheathing press will have been centrifugallypurified so as to be substantially free of oxides or other impurities,and thus permit of applying metal sheaths to cables with the metalsheaths substantially perfect and free from oxides or other impurities,throughout all portions of the sheath.

The invention may be carried out in other specific ways than thoseherein set forth without departing from the spirit and essentialcharacteristics of the invention, and the present embodiments are,therefore, to be considered in all respects as illustrative and notrestrictive, and all changes coming within the meaning and equivalencyrange of the appended claims are intended to be embraced therein.

I claim: 1. The method of applying lead-base metallic sheaths toelectric cables, comprising: centrifugally removing impurities fromlead-base sheath metal while in a molten condition and ing press forforming lead-base sheath metal into a sheath on a cable; a centrifugalseparator constructed and arranged to retain a substantial body ofmolten lead-base sheath metal and-centrifugally remove impurities fromthe said molten metal by causing the impurities to travel to theinterior portion of the body of molten metal; a tank for receiving saidcentrifugally purified lead-base sheath metal from said centrifugalseparator; and means for conveying said centrifugally purified lead-basesheath metal from said tank into said sheathing press. I

3. Apparatus for applying metallic sheaths to cables, including: asheathing press for forming sheath metal into a sheath on a cable; acentrifugal separator for centrifugally removing impurities from sheathmetal while in a molten condition; a tank adapted to recirculate moltensheath metal through said centrifugal separator; and means for conveyingsaid centrifugally purified sheath metal into said sheathing press.

4. Apparatus for applying metallic sheaths to cables, including: asheathing press for forming sheath metal into a sheath on a cable; acentrifugal separator for centrifugally removing impurities from sheathmetal while in a molten condition; a tank surrounding said centrifugalseparator and adapted to recirculate molten sheath metal through saidcentrifugal separator;

and means for conveying said centrifugally purl fied sheath metal intosaid sheathing press.

5. Apparatus for applying metallic sheaths to cables, including: asheathing press for forming sheath metal into a sheath on a cable; acentrifugal separator for centrifugally removing impurities from sheathmetal while in a molten condition; drain means communicating with thelower end of said centrifugal separator; and means for conveying saidcentrifugally purified sheath metal into said sheathing press.

6. Apparatus for applying metallic sheaths to cables, including: amelting chamber for sheath metal; asheathing press for forming sheathmetal into a sheath on a cable; and a centrifugal separator forcentrifugally removing impurities from sheath metal while in a moltencondition having an inlet end communicating with said melting chamberfor receiving molten sheath metal therefrom and an outlet endcommunicating with said sheathing press for conveying said centrifugallypurified sheath metal into said sheathing press.

7. Apparatus for applying lead-base metallic sheaths to electric cables,including: a centrifugal separator constructed and arranged to retain asubstantial body of molten lead-base sheath metal and centrifugallyremove impurities from the said molten metal by causing the impuritiesto travel to the interior portion of the body of molten metal, and tocause purified molten metal to be removed from the said centrifugalseparator from the exterior portion of the body of molten metal withoutcarrying with it any of the impurities which had been caused to travelto the interior portion of the body of molten metal.

8. Apparatus for applying lead-base metallic sheaths to electric cables,including: a centrif- 1188.1- separator constructed and arranged toretain a substantial body of molten lead-base sheath metal andcentrifugally remove impurities from the said molten metal by causingthe impurities to travel to the interior portion of the body of moltenmetal, and to cause purified molten metal to be removed from the saidcentrifugal separator from the exterior portion of the body of moltenmetal without carrying with it any of the impurities which hadbeen'caused to travel to the interior portion of the body of moltenmetal, said centrifugal separator having an inner inlet and an outeroutlet for the molten metal. v

IEIGH E. FOGG.

